Ectoparasites as numerical dominant species in parasite community of Trachelyopterus striatulus (Siluriformes: Auchenipteridae) from Guandu River, southeastern Brazil

sixty specimens of singing catfish trachelyopterus striatulus (steindachner, 1877) (siluriformes: auchenipteridae) collected from guandu river (22o 48' 32" s and 43o 37' 35" w), in the state of rio de janeiro, brazil from october 2006 to march 2009, were necropsied to study their parasites. from the 60 specimens of t. striatulus examined 57 were parasitised by at least one parasite species. the majority of the parasite specimens collected were monogeneans followed by nematoda, digenea and hirudinea. cosmetocleithrum sp. was the numerically predominant species with highest prevalence and abundance. the parasites of t. striatulus showed the typical pattern of aggregated distribution. no parasite species showed significant correlation between the body total length of the host and their abundance. the mean parasite species richness was not correlated with the host's total body length and sex. values of the brillouin index of diversity had a mean of h = 0.083 ± 0.136.